Back in 1999, the original “Walking with Dinosaurs” documentary series, produced by the BBC, used state-of-the-art computer animation to depict the lives of long-extinct lizards as if they were the subjects of a typical nature documentary. The shows admirably blended entertaining spectacle with informative narration without Disney-fying their subjects.

It was worrisome, then, when the trailers for “Walking with Dinosaurs 3-D” made it look like both the story and the style condescended to the kiddie market. There’s a plot, for instance, and it’s a pretty familiar one: our young hero, Patchi the Pachyrhinosaurus, must learn to survive when his parents are both killed and his bully of a big brother, Scowler, becomes the leader of the herd. These dinosaurs talk, Patchi in the voice of Justin Long, his avian sidekick in the voice of John Leguizamo.

Yes, I said “avian sidekick.” And, yes, I said “Justin Long.” But don’t let that stop you — even with all these strikes against it, the movie manages to entertain and educate, despite the poop and vomit jokes it sometimes relies on. It’s helpful that we hear the dinos in voice-over, so there’s no unrealistic mouth movement going on. It’s as if the movie was dubbed from Late Cretaceous into modern English; an annoyance, but not a deal-breaker. If the narration were eliminated, the whole thing would still make sense, just with fewer jokes (hopefully that’s an option on the eventual Blu-ray release).

Also, of course, “state-of-the-art computer animation” means something very different today than it did in 1999. Against live-action backdrops, the 3-D visuals are brilliant and mostly accurate, as they depict a range of species including the predatory Gorgosaurus (why are carnivores always the bad guys?), the soaring Quetzalcoatlus, and the feathered Alexornis.

Purists may still quail at the little bit of anthropomorphism going on (as well as the dorky live-action framing scenes starring, for some reason, Karl Urban), but it seems a small price to pay to broaden the audience for a family film that seeks to do more than just entertain.

The lowdown: A young Pachyrhinosaurusgrows up in the Late Cretaceous period, dealing with a bullying brother, a crush on a fellow herd member and the dangers of dinosaur life. This offshoot of the BBC documentary series features animation stunning and accurate enough to make up for its simple story and unnecessary voice-over dialogue.